Abstract
High-frequency broadband (200–300 kHz) acoustic scattering techniques have been used to observe the diffusive regime of double-diffusive convection in the laboratory. Pulse compression signal processing techniques allow (1) centimetre-scale interface thickness to be rapidly, remotely, and continuously measured, (2) the evolution, and ultimate merging, of multiple interfaces to be observed at high-resolution, and (3) convection cells within the surrounding mixed layers to be observed. The acoustically measured interface thickness, combined with knowledge of the slowly varying temperatures within the surrounding layers, in turn allows the direct estimation of double-diffusive heat and buoyancy fluxes. The acoustically derived interface thickness, interfacial fluxes and migration rates are shown to support established theory. Acoustic techniques complement traditional laboratory sampling methods and provide enhanced capabilities for observing the diffusive regime of double-diffusion in the ocean.
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Acknowledgments
We thank Ray Schmitt for the use of his tank, Dan Kelley for useful comments on the manuscript, and the Doherty Foundation for funding Tetjana’s postdoctoral scholarship at WHOI. Funding for this project was provided by the Ocean Acoustics program at the Office of Naval Research, and by the WHOI Cecil and Ida Greene Technology Award.
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Ross, T., Lavery, A. Laboratory observations of double-diffusive convection using high-frequency broadband acoustics. Exp Fluids 46, 355–364 (2009). https://doi.org/10.1007/s00348-008-0570-9
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DOI: https://doi.org/10.1007/s00348-008-0570-9